IDENTIFYING SOURCES OF ORGANIC CARBON IN SURFACE SEDIMENTS OF LAPTEV SEA SHELF USING A ROCK-EVAL APPROACH

Abstract

An increasing rate of degradation of coastal and subsea permafrost leads to remobilization of huge amounts of organic carbon. To know how this remobilized carbon behaves while being transported through the land-shelf system is crucially important for understanding an extremely fragile Arctic ecosystem. This study is aimed at tracing the geochemical signals of organic matter along the profile from the coastal zone to the continental slope of the Laptev Sea, using the Rock-Eval approach. We investigated surface sediment samples obtained during the Arctic marine expeditions of 2018–2019 on the R/V “Akademik Mstislav Keldysh». The most active oxidation of organic matter, exported with river runoff and products of coastal erosion, occurs in the coastal zone at a depth of several tens of meters. A significant effect on the organic matter composition is exerted by the sediment export from Novosibirsk Islands eroding coastlines. We assume that various products carried by river runoff and coastal erosion are characterized by various signatures detected by the Rock-Eval method (e.g., the OI and Tpeak values). It is also shown that the mineral matrix does not seem to provide a first-order control on preventing organic matter degradation during transport from the coastal zone to deep-sea basins.

Keywords

• pyrolysis
• bottom sediments
• organic matter
• hydrocarbons
• arctic
• laptev sea